We can track errors by using `pageContext.errorWhileRendering`:

```js
// server.js

const { createPageRenderer } = require('vite-plugin-ssr')

const renderPage = createPageRenderer(/* ... */)
app.get('*', async (req, res, next) => {
  const pageContext = await renderPage({ url: req.url })

  // An error occured during server-side rendering
  if (pageContext.errorWhileRendering) {
    myErrorTracker(pageContext.errorWhileRendering)
  }

  // ...
})
```

So that we can, for example, install the tracker code of a tracking service such as [Sentry](https://sentry.io/), [Bugsnag](https://www.bugsnag.com/), or [Rollbar](https://rollbar.com/).
